The popularity of the game of golf has increased immensely in recent decades. Golfers at all skill levels seek to improve their performance, lower their golf scores, and reach that next performance “level.” Most amateur golfers play with the same set of clubs for an extended period of time. For example, a set of irons may be used by a golfer for periods in excess of five and sometimes ten years.
Despite the various technological improvements, golf remains a difficult game to play at a high level. For a golf ball to reliably fly straight and in the desired direction, a golf club must meet the golf ball square (or substantially square) to the desired target path. Moreover, the golf club must meet the golf ball at or close to a desired location on the club head face (i.e., on or near a “desired” or “optimal” ball contact location) to reliably fly straight, in the desired direction, and for a desired distance. Off-center hits may tend to “twist” the club face when it contacts the ball, thereby sending the ball in the wrong direction, imparting undesired hook or slice spin, and/or robbing the shot of distance. Club face/ball contact that deviates from squared contact and/or is located away from the club's desired ball contact location, even by a relatively minor amount, also can launch the golf ball in the wrong direction, often with undesired hook or slice spin, and/or can rob the shot of distance. Inasmuch as it is difficult for a golfer to maintain a square club head, a squared contact can still result in undesirable results.
As a golf club strikes a ball time and again, golf club performance begins to deteriorate. For example, the amount and direction of spin imparted on a golf ball by the face of a golf club can gradually change over time as the face of the club changes due to repeated hits of golf balls. Nicks in the face of a club may cause undesired spin characteristics and/or loss of the ability to impart spin. Also, the grooves of a club can become shallower or uneven as the face of the club gets worn. This fact is particularly true for wedges or other clubs that are used for hitting balls out of the sand, dirt, or other abrasive terrain. Repeated hits can actually modify the face of a club itself. In addition, the hosel may lose some of its stiffness resulting in undesired energy dissipation from its increasing flexibility. The above-described gradual deterioration in club head performance over time is typically transparent to the golfer.